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yonghong-songAlexei Starovoitov
yonghong-song
authored and
Alexei Starovoitov
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selftests/bpf: add a selftest with __user tag
Added a selftest with three__user usages: a __user pointer-type argument in bpf_testmod, a __user pointer-type struct member in bpf_testmod, and a __user pointer-type struct member in vmlinux. In all cases, directly accessing the user memory will result verification failure. $ ./test_progs -v -n 22/3 ... libbpf: prog 'test_user1': BPF program load failed: Permission denied libbpf: prog 'test_user1': -- BEGIN PROG LOAD LOG -- R1 type=ctx expected=fp 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 ; int BPF_PROG(test_user1, struct bpf_testmod_btf_type_tag_1 *arg) 0: (79) r1 = *(u64 *)(r1 +0) func 'bpf_testmod_test_btf_type_tag_user_1' arg0 has btf_id 136561 type STRUCT 'bpf_testmod_btf_type_tag_1' 1: R1_w=user_ptr_bpf_testmod_btf_type_tag_1(id=0,off=0,imm=0) ; g = arg->a; 1: (61) r1 = *(u32 *)(r1 +0) R1 invalid mem access 'user_ptr_' ... #22/3 btf_tag/btf_type_tag_user_mod1:OK $ ./test_progs -v -n 22/4 ... libbpf: prog 'test_user2': BPF program load failed: Permission denied libbpf: prog 'test_user2': -- BEGIN PROG LOAD LOG -- R1 type=ctx expected=fp 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 ; int BPF_PROG(test_user2, struct bpf_testmod_btf_type_tag_2 *arg) 0: (79) r1 = *(u64 *)(r1 +0) func 'bpf_testmod_test_btf_type_tag_user_2' arg0 has btf_id 136563 type STRUCT 'bpf_testmod_btf_type_tag_2' 1: R1_w=ptr_bpf_testmod_btf_type_tag_2(id=0,off=0,imm=0) ; g = arg->p->a; 1: (79) r1 = *(u64 *)(r1 +0) ; R1_w=user_ptr_bpf_testmod_btf_type_tag_1(id=0,off=0,imm=0) ; g = arg->p->a; 2: (61) r1 = *(u32 *)(r1 +0) R1 invalid mem access 'user_ptr_' ... #22/4 btf_tag/btf_type_tag_user_mod2:OK $ ./test_progs -v -n 22/5 ... libbpf: prog 'test_sys_getsockname': BPF program load failed: Permission denied libbpf: prog 'test_sys_getsockname': -- BEGIN PROG LOAD LOG -- R1 type=ctx expected=fp 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 ; int BPF_PROG(test_sys_getsockname, int fd, struct sockaddr *usockaddr, 0: (79) r1 = *(u64 *)(r1 +8) func '__sys_getsockname' arg1 has btf_id 2319 type STRUCT 'sockaddr' 1: R1_w=user_ptr_sockaddr(id=0,off=0,imm=0) ; g = usockaddr->sa_family; 1: (69) r1 = *(u16 *)(r1 +0) R1 invalid mem access 'user_ptr_' ... #22/5 btf_tag/btf_type_tag_user_vmlinux:OK Signed-off-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/r/20220127154616.659314-1-yhs@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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‎tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,24 @@ bpf_testmod_test_mod_kfunc(int i)
2121
*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
2222
}
2323

24+
struct bpf_testmod_btf_type_tag_1 {
25+
int a;
26+
};
27+
28+
struct bpf_testmod_btf_type_tag_2 {
29+
struct bpf_testmod_btf_type_tag_1 __user *p;
30+
};
31+
32+
noinline int
33+
bpf_testmod_test_btf_type_tag_user_1(struct bpf_testmod_btf_type_tag_1 __user *arg) {
34+
return arg->a;
35+
}
36+
37+
noinline int
38+
bpf_testmod_test_btf_type_tag_user_2(struct bpf_testmod_btf_type_tag_2 *arg) {
39+
return arg->p->a;
40+
}
41+
2442
noinline int bpf_testmod_loop_test(int n)
2543
{
2644
int i, sum = 0;

‎tools/testing/selftests/bpf/prog_tests/btf_tag.c‎

Lines changed: 93 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,15 @@
11
// SPDX-License-Identifier: GPL-2.0
22
/* Copyright (c) 2021 Facebook */
33
#include <test_progs.h>
4+
#include <bpf/btf.h>
45
#include "test_btf_decl_tag.skel.h"
56

67
/* struct btf_type_tag_test is referenced in btf_type_tag.skel.h */
78
struct btf_type_tag_test {
89
int **p;
910
};
1011
#include "btf_type_tag.skel.h"
12+
#include "btf_type_tag_user.skel.h"
1113

1214
static void test_btf_decl_tag(void)
1315
{
@@ -41,10 +43,101 @@ static void test_btf_type_tag(void)
4143
btf_type_tag__destroy(skel);
4244
}
4345

46+
static void test_btf_type_tag_mod_user(bool load_test_user1)
47+
{
48+
const char *module_name = "bpf_testmod";
49+
struct btf *vmlinux_btf, *module_btf;
50+
struct btf_type_tag_user *skel;
51+
__s32 type_id;
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int err;
53+
54+
if (!env.has_testmod) {
55+
test__skip();
56+
return;
57+
}
58+
59+
/* skip the test if the module does not have __user tags */
60+
vmlinux_btf = btf__load_vmlinux_btf();
61+
if (!ASSERT_OK_PTR(vmlinux_btf, "could not load vmlinux BTF"))
62+
return;
63+
64+
module_btf = btf__load_module_btf(module_name, vmlinux_btf);
65+
if (!ASSERT_OK_PTR(module_btf, "could not load module BTF"))
66+
goto free_vmlinux_btf;
67+
68+
type_id = btf__find_by_name_kind(module_btf, "user", BTF_KIND_TYPE_TAG);
69+
if (type_id <= 0) {
70+
printf("%s:SKIP: btf_type_tag attribute not in %s", __func__, module_name);
71+
test__skip();
72+
goto free_module_btf;
73+
}
74+
75+
skel = btf_type_tag_user__open();
76+
if (!ASSERT_OK_PTR(skel, "btf_type_tag_user"))
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goto free_module_btf;
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79+
bpf_program__set_autoload(skel->progs.test_sys_getsockname, false);
80+
if (load_test_user1)
81+
bpf_program__set_autoload(skel->progs.test_user2, false);
82+
else
83+
bpf_program__set_autoload(skel->progs.test_user1, false);
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err = btf_type_tag_user__load(skel);
86+
ASSERT_ERR(err, "btf_type_tag_user");
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btf_type_tag_user__destroy(skel);
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90+
free_module_btf:
91+
btf__free(module_btf);
92+
free_vmlinux_btf:
93+
btf__free(vmlinux_btf);
94+
}
95+
96+
static void test_btf_type_tag_vmlinux_user(void)
97+
{
98+
struct btf_type_tag_user *skel;
99+
struct btf *vmlinux_btf;
100+
__s32 type_id;
101+
int err;
102+
103+
/* skip the test if the vmlinux does not have __user tags */
104+
vmlinux_btf = btf__load_vmlinux_btf();
105+
if (!ASSERT_OK_PTR(vmlinux_btf, "could not load vmlinux BTF"))
106+
return;
107+
108+
type_id = btf__find_by_name_kind(vmlinux_btf, "user", BTF_KIND_TYPE_TAG);
109+
if (type_id <= 0) {
110+
printf("%s:SKIP: btf_type_tag attribute not in vmlinux btf", __func__);
111+
test__skip();
112+
goto free_vmlinux_btf;
113+
}
114+
115+
skel = btf_type_tag_user__open();
116+
if (!ASSERT_OK_PTR(skel, "btf_type_tag_user"))
117+
goto free_vmlinux_btf;
118+
119+
bpf_program__set_autoload(skel->progs.test_user2, false);
120+
bpf_program__set_autoload(skel->progs.test_user1, false);
121+
122+
err = btf_type_tag_user__load(skel);
123+
ASSERT_ERR(err, "btf_type_tag_user");
124+
125+
btf_type_tag_user__destroy(skel);
126+
127+
free_vmlinux_btf:
128+
btf__free(vmlinux_btf);
129+
}
130+
44131
void test_btf_tag(void)
45132
{
46133
if (test__start_subtest("btf_decl_tag"))
47134
test_btf_decl_tag();
48135
if (test__start_subtest("btf_type_tag"))
49136
test_btf_type_tag();
137+
if (test__start_subtest("btf_type_tag_user_mod1"))
138+
test_btf_type_tag_mod_user(true);
139+
if (test__start_subtest("btf_type_tag_user_mod2"))
140+
test_btf_type_tag_mod_user(false);
141+
if (test__start_subtest("btf_type_tag_sys_user_vmlinux"))
142+
test_btf_type_tag_vmlinux_user();
50143
}

‎tools/testing/selftests/bpf/progs/btf_type_tag_user.c‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
// SPDX-License-Identifier: GPL-2.0
2+
/* Copyright (c) 2022 Facebook */
3+
#include "vmlinux.h"
4+
#include <bpf/bpf_helpers.h>
5+
#include <bpf/bpf_tracing.h>
6+
7+
struct bpf_testmod_btf_type_tag_1 {
8+
int a;
9+
};
10+
11+
struct bpf_testmod_btf_type_tag_2 {
12+
struct bpf_testmod_btf_type_tag_1 *p;
13+
};
14+
15+
int g;
16+
17+
SEC("fentry/bpf_testmod_test_btf_type_tag_user_1")
18+
int BPF_PROG(test_user1, struct bpf_testmod_btf_type_tag_1 *arg)
19+
{
20+
g = arg->a;
21+
return 0;
22+
}
23+
24+
SEC("fentry/bpf_testmod_test_btf_type_tag_user_2")
25+
int BPF_PROG(test_user2, struct bpf_testmod_btf_type_tag_2 *arg)
26+
{
27+
g = arg->p->a;
28+
return 0;
29+
}
30+
31+
/* int __sys_getsockname(int fd, struct sockaddr __user *usockaddr,
32+
* int __user *usockaddr_len);
33+
*/
34+
SEC("fentry/__sys_getsockname")
35+
int BPF_PROG(test_sys_getsockname, int fd, struct sockaddr *usockaddr,
36+
int *usockaddr_len)
37+
{
38+
g = usockaddr->sa_family;
39+
return 0;
40+
}

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